Received-SPF: pass (google.com: domain of linux-kernel+bounces-87571-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Thu, 29 Feb 2024 21:19:34 +0000
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Wei Fang <wei.fang@nxp.com>, "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Florian Fainelli <florian.fainelli@broadcom.com>,
	kernel@pengutronix.de, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, Shenwei Wang <shenwei.wang@nxp.com>,
	Clark Wang <xiaoning.wang@nxp.com>,
	NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [PATCH net-next v7 5/8] net: phy: Immediately call adjust_link
 if only tx_lpi_enabled changes
Message-ID: <ZeD05pY1RdKNtrDZ@shell.armlinux.org.uk>
References: <20240229140800.3420180-1-o.rempel@pengutronix.de>
 <20240229140800.3420180-6-o.rempel@pengutronix.de>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240229140800.3420180-6-o.rempel@pengutronix.de>
Sender: Russell King (Oracle) <linux@armlinux.org.uk>

On Thu, Feb 29, 2024 at 03:07:57PM +0100, Oleksij Rempel wrote:
> +static void phy_ethtool_set_eee_noneg(struct phy_device *phydev,
> +				      struct ethtool_keee *data)
> +{
> +	if (phydev->eee_cfg.tx_lpi_enabled != data->tx_lpi_enabled ||
> +	    phydev->eee_cfg.tx_lpi_timer != data->tx_lpi_timer) {
> +		eee_to_eeecfg(data, &phydev->eee_cfg);
> +		phydev->enable_tx_lpi = eeecfg_mac_can_tx_lpi(&phydev->eee_cfg);
> +		if (phydev->link) {
> +			phy_link_down(phydev);
> +			phy_link_up(phydev);

Unfortunately, this isn't sufficient in all cases. Phylink will be fine
with this though.

If we take a look at fec_enet_adjust_link(), then we can see it tests
phydev->link directly (which it has to, because there's nothing else
to determine whether the link is up or down. FEC will cope with its
fec_enet_adjust_link() being called with no changes however.

In order to properly resolve this, I think we need:

		if (phydev->link) {
			phydev->link = false;
			phy_link_down(phydev);
			phydev->link = true;
			phy_link_up(phydev);

to properly avoid the issue I've referred to.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!